A mouse is distinguished from other cursor control systems such as light pens and digitizers in that those other systems utilize an active surface or grid in communication with a cursor, pen, or the like. A mouse is utilized on a passive surface, such as a desk top or papers on the desk top, with motion of the mouse producing corresponding motion of a cursor dot on a visual display.
There are two basic types of mice available heretofor, namely mechanical and optical mice. The first type of mechanical mouse is comprised generally of a housing supported for rolling motion by two wheels, the wheels being oriented perpendicular with respect to each other for rolling motion in perpendicular axes. Thus, when the mouse is moved on a work surface, the slipping and rolling of each wheel corresponds to direction and distance motion in one axis. The rotation of the wheels is translated into signals used to produce corresponding movement of a cursor on a cathode ray tube display. Engelbart U.S. Pat. No. 3,451,541 and Hawley U.S. Pat. No. 3,892,963 disclose examples of two-wheel mechanical mice.
In a second type of mechanical mouse, the housing mounts a sphere which rolls on the work surface, and the housing further mounts wheels which are driven by the sphere, the wheels having transducers associated therewith for providing signals indicative of motion of the mouse in two axes. A mouse of the spherical ball type is disclosed in Rider U.S. Pat. No. 3,835,464. The spherical ball mouse eliminates some of the problem of dragging one wheel sideways when motion is not in the plane of that wheel, but slippage of the wheels and of the sphere with respect to the work surface remain a problem. Reliability has been limited by a susceptibility to dirt from the surface. Mechanical mice have generally been expensive and difficult to manufacture in that they require high precision parts.
The optical mouse is comprised of a housing including a light source and light sensors, used in combination with a specially patterned work surface. As the mouse is moved across the work surface, its light sensors can detect the direction and extent of movement through pattern recognition, and provide signals for controlling corresponding movement of a cursor on a cathode ray tube. An optical mouse is described in Kirsch U.S. Pat. No. 4,364,035. The disadvantage of the optical mouse is the requirement of a special patterned pad, the necessity of the pad rather than the mouse itself setting the axes of movement and the inconvenience of having to clear the pad of other work material when the mouse is in use.
A third type of mouse, which has not gained commercial acceptance, is disclosed in Page U.S. Pat. No. 4,303,914. This mouse comprises a housing mounting two conventional piezo electric audio pick-ups, with the audio pick-ups oriented at right angles to each other. When the styli of the audio pick-ups are drawn across a microscopically textured surface, such as a sheet of paper, each audio pick-up produces a succession of uni-directional pulses with the polarity of the pulses being indicative of the direction of motion along a selected axis. The extent of motion is determined by a count of pulses, the pulse information being used to control movement of a cursor dot on a cathode ray tube. None of these mice has proven completely satisfactory, with complexity and cost being important drawbacks in the evolving widescale need for mouse devices.